Distribution and Evaluation of Heavy Metals in Agricultural Soil in Southern Area of Beijing

The southern area of Beijing includes Tongzhou, Daxing, Fengtai and Fangshan District. The soil in this area has been polluted by heavy metals. In order to prevent this area from further pollution and improve the agriculture product quality, it is imperative to study the heavy metals distribution and their pollution effects. Twenty-five soil samples are taken, and among these, the soil from JN1 profile is taken in the spring (the last ten days of March) and autumn (the first ten days of November) respectively. The distribution and pollution evaluation for Pb, Zn, Cu, Cd and As are mainly researched. The contents of heavy metals in the soils are different in this region, with the order in term of the content being ZnPbCuAsCd. From the east to the west in this area, the contents of soil heavy metals decrease gradually, and along the rivers and highways, the contents of soil heavy metals also decrease from the inside to the outside gradually. The heavy metals concentrate on the upper horizons, especially the 0~20 cm horizon in the soil profile, and decrease abruptly below the depth of 20 cm. The contents of soil heavy metals in the spring are higher than those in the autumn. All the heavy metal pollution indexes surplus 1.0, suggesting that the soils in this area are polluted by the heavy metals slightly.